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glibc 2.2.5 connect issue

From: Me
Subject: glibc 2.2.5 connect issue
Date: Fri, 8 Feb 2002 10:20:24 -0800

I have a simple test program which fails...
The issue is a combination of factors...
   a> load a shared library (dlopen, dlsym)
   b> invoke a function in that library which creates a thread
   c> have that thread attempt a connect() on a socket().

The connect() will fail with -1, but will not set errno.

Attached are the following three files in a .tgz format....

I'm running a sorcery distribution with linux kernel version 2.4.17 or
2.5.3.  I have traced the code, the __libc_connect() invokes a syscall, the
result code -115 is returned in eax, but under this set of circumstances
errno() is not set with any value.  I have tested a couple possible errors -
a> ewouldblock b>addressnotsupported...
I am currently building 2.2.4 version of glibc....

I have tested this using gcc 2.96(good system) and gcc 2.95.3(failing
system) - copying the same binary to 2 systems (other running a kernel
2.4.7-10. 2.2.16), they both work, pretty much since the result from the int
$0x80 syscall is correct, I'm going to point my finger at glibc.

kernel 2.4.17 gcc 2.95.3 glibc 2.2.5 fails
kernel 2.5.3 gcc 2.95.3 glibc 2.2.5 fails
kernel 2.2.16-22 gcc 2.96 glibc 2.1.92 (redhat 7.1) succeeds
kernel 2.4.7-10 gcc 2.96 glibc 2.2.4 (redhat 7.2) fails

hmmm well guess 2.2.4 won't work anyhow.. aborted that installation....

---- Makefile ---

LDFLAGS= -g # link for no debug loggings

all: loader puser puser.so

 #echo 'Loader loads .so, .so makes a thread that '
 #echo 'attempts to connect a nonblocking socket...'
 export LD_LIBRARY_PATH=./ && ./loader
 #echo 'program makes a thread which attempts to connect...'

 gcc -g -o loader loader.c -ldl

puser:    puser.o
puser.so: puser.o
 ld -shared $(LDFLAGS) -o $@ $< -lpthread
puser.o:  puser.c

-- end makefile ---
-- loader.c ---
#include <stdio.h>
#include <errno.h>
#include <dlfcn.h>

int main( int argc, char **argv )
    void* hModule;
    int (*nextmain)(int argc, char **argv );
    hModule = dlopen( "puser.so", RTLD_NOW );
    if( !hModule )
        fprintf( stderr, "Failed to load program puser(%s)\n", dlerror() );
        nextmain = dlsym( hModule, "main" );
        return nextmain( argc-2, argv+2 );
    return 0;
-- end loader.c --
-- puser.c ---
#include <stdio.h>

#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netdb.h>
#include <errno.h>

#include <sys/ioctl.h>

//struct sockaddr sa={2,{0,23,127,0,0,1}};
struct sockaddr sa={2,{0,23,255,255,255,255}};

int DedicatedConnect( void )
    int Socket;
    Socket=socket( PF_INET, SOCK_STREAM, IPPROTO_TCP );
    if (Socket < 0)
        printf( "Create socket failed.\n" );
        return 0;
        int err;
        // optional code here... just plain doesn't work at all...
            int t = 1;
            ioctl( Socket, FIONBIO, &t );
        errno = 50000;
        if( err = connect( Socket, &sa, sizeof(sa) ) )
            unsigned long dwError;
            dwError = errno;
            // this is the expected error... but connect never sets errno...
            if( dwError != EINPROGRESS )
                printf( "errno will be whatever was before connect...\n" );
                printf( "Connect FAIL: socket:%d connect:%d errno:%d\n",
Socket, err, dwError );
                return 0;
                printf( "Expected result - success - connection in
progress\n" );
            printf( "Success? %d", err );
    return 1;

void *thread( void *junk )
    if( !DedicatedConnect() )
        printf( "failed to open\n" );
        return 0;
    while( 1 )
    return NULL;

int main( char argc, char** argv )
    pthread_t junk;
    pthread_create( &junk, NULL, thread, NULL );
    printf( "Press return to exit\n" );
    return 0;
-- end puser.c ---

PLEASE respond if there's a fix...

Attachment: testconnect.tgz
Description: application/compressed

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